In a joint, the range of motion depends upon the anatomy of that joint and on the particular genetics of each individual. Typically, joints move in two directions, flexion and extension. Flexion is to bend the joint and extension is to straighten the joint; however, in the orthopedic convention some joints only flex. For example, the ankle has dorsiflexion and plantarflexion. Other joints not only flex and extend, they rotate. For example, the elbow joint has supination and pronation, which is rotation of the hand about the longitudinal axis of the forearm placing the palm up or the palm down.
When a joint is injured either by trauma or by surgery, scar tissue can form, often resulting in flexion or extension contractures. Such conditions can limit the range of motion of the joint, limiting flexion (in the case of an extension contracture) or extension (in the case of a flexion contracture) of the injured joint. It is often possible to correct this condition by use of a range-of-motion (ROM) orthosis.
ROM orthoses are devices commonly used during physical rehabilitative therapy to increase the range-of-motion over which the patient can flex or extend the joint. Commercially available ROM orthoses are typically attached on opposite members of the joint and apply a torque to rotate the joint in opposition to the contraction. The force is gradually increased to increase the working range or angle of joint motion. Exemplary orthoses include U.S. Pat. Nos. 6,599,263, entitled “Shoulder Orthosis;” 6,113,562, entitled “Shoulder Orthosis;” 5,848,979, entitled “Orthosis;” 5,685,830, entitled “Adjustable Orthosis Having One-Piece Connector Section for Flexing;” 5,611,764, entitled “Method of Increasing Range of Motion;” 5,503,619, entitled “Orthosis for Bending Wrists;” 5,456,268, entitled “Adjustable Orthosis;” 5,453,075, entitled “Orthosis with Distraction through Range of Motion;” 5,395,303, entitled “Orthosis with Distraction through Range of Motion;” 5,365,947, entitled “Adjustable Orthosis;” 5,285,773, entitled “Orthosis with Distraction through Range of Motion;” 5,213,095, entitled “Orthosis with Joint Distraction;” and 5,167,612, entitled “Adjustable Orthosis,” all to Bonutti and herein are expressly incorporated by reference in their entirety.